$D0B3/53427/SCPU+67: Enhanced Optimization Register (V2 only!)
+----------+---------------------------------------------------+
| Bits 7-0 | 00xxx1BZ = VIC-Bank 0, $0000 - $3FFF | |
| | 01xxx0B0 = VIC-Bank 1, $4000 - $7FFF |
| | 00xxx0B0 = VIC-Bank 2, $8000 - $BFFF (GEOS) |
| | 01xxx1B0 = VIC-Bank 3, $C000 - $FFFF |
| | 10xxx0B0 = BASIC Opt., $0400 - $07FF |
| | 11xxx00Z = No Opt all mem, $0:0000 - $1:FFFF |
| | V2: Default |
| | 11xxx1BZ = No Opt per bank, $0000 - $FFFF |
| | 10xxx100 = Full optimization (no mirroring) |
+----------+---------------------------------------------------+
This register is read only with hardware registers disabled,
Read/Write with hardware registers enabled.
Changing values in this area affects all other optimization mode
registers, and changing other optimization mode registers affect
this location. The B-flag assigns control of this register to a
specific C128 bank (0 = Bank 0, 1 = Bank 1), while the Z-flag
controls mirroring of ZeroPage and Stack memory ($0000 - $01FF)
(0 = mirroring on, 1 = mirroring off). Default for Z is 1, B is 0.